<?
/*
diff.php

Copyright (C) 1992 Free Software Foundation, Inc. Francois Pinard <pinard@iro.umontreal.ca>.
Copyright (C) 2000, 2001 Geoffrey T. Dairiki <dairiki@dairiki.org>
Copyright 2002,2003,2004  David DELON
Copyright 2002  Patrick PAUL
Copyright 2003  Eric FELDSTEIN

This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
*/
  // Side : a string for wdiff

  class Side {
      var $position;
      var $cursor;
      var $content;
      var $character;
      var $directive;
      var $argument;
      var $length;

      function Side($content) {
         $this->content=$content;
         $this->position=0;
         $this->cursor=0;
         $this->directive='';
         $this->argument=array();
         $this->length=strlen($this->content);
         $this->character=substr($this->content,0,1);
         
      }

      function getposition() {
         return $this->position;
      }

      function getcharacter() {
         return $this->character;
      }

      function getdirective() {
         return $this->directive;
      }

      function getargument() {
         return $this->argument;
      }

      function nextchar() {
         $this->cursor++; 
         $this->character=substr($this->content,$this->cursor,1);
      }

      function copy_until_ordinal($ordinal,&$out)  {
         while ($this->position < $ordinal) {
      $this->copy_whitespace($out);
      $this->copy_word($out);
         }
      }

      function skip_until_ordinal($ordinal) {
         while ($this->position < $ordinal) {
      $this->skip_whitespace();
      $this->skip_word();
         }
      }

      function split_file_into_words (&$out) {
         while (!$this->isend()) {
     $this->skip_whitespace();
     if ($this->isend()) {
       break;
     }
     $this->copy_word($out);
     $out .="\n";
         }
      }
      
      function init() {
         $this->position=0;
         $this->cursor=0;
         $this->directive='';
         $this->argument=array();
         $this->character=substr($this->content,0,1);
      }     

      function isspace($char) {
        if (preg_match("/([[:space:]]|\*)/",$char)) return true;
        return false;
      }

      function isdigit($char) {
        if (preg_match('/[[:digit:]]/',$char)) return true;
        return false;
      }

      function isend() {
        if (($this->cursor)>=($this->length)) return true;
        return false;
      }

      function copy_whitespace(&$out)  {
     while (!$this->isend() && $this->isspace($this->character)) {
        $out .=$this->character;
        $this->nextchar();
     }
      }

      function skip_whitespace()  {
     while (!$this->isend() && $this->isspace($this->character)) {
        $this->nextchar();
     }
      }

      function skip_line()  {
        while (!$this->isend() && !$this->isdigit($this->character)) {
      while (!$this->isend() && $this->character!="\n")
      $this->nextchar();
      if($this->character=="\n")
          $this->nextchar();
         }
       }

       function copy_word(&$out) {
     while (!$this->isend() && !($this->isspace($this->character))) {
        $out.=$this->character;
        $this->nextchar();
     }
     $this->position++;
       }

       function skip_word() {

     while (!$this->isend() && !($this->isspace($this->character))) {
        $this->nextchar();
     }
     $this->position++;
       }


   function decode_directive_line() {

    $value=0;                    
    $state=0;                   
    $error=0;                  

    while (!$error && $state < 4) {
        if ($this->isdigit($this->character)) {
      $value = 0;
      while($this->isdigit($this->character)) {
          $value = 10 * $value + $this->character - '0';
          $this->nextchar(); 
      }
        }
        else if ($state != 1 && $state != 3)
        $error = 1;

        /* Assign the proper value.  */

        $this->argument[$state] = $value;

        /* Skip the following character.  */

        switch ($state) {
    case 0:
    case 2:
      if ($this->character == ',')
         $this->nextchar();
      break;

    case 1:
      if ($this->character == 'a' || $this->character == 'd' || $this->character == 'c') {
          $this->directive = $this->character;
          $this->nextchar();
        }
      else
        $error = 1;
      break;

      case 3:
      if ($this->character != "\n")
        $error = 1;
        break;
      }
     $state++;
        }

    /* Complete reading of the line and return success value.  */

    while ((!$this->isend()) && ($this->character != "\n")) {
        $this->nextchar();
    }
    if ($this->character == "\n")
        $this->nextchar();

    return !$error;
  }



  }

  // difflib
  //
  // A PHP diff engine for phpwiki.
  //
  // Copyright (C) 2000, 2001 Geoffrey T. Dairiki <dairiki@dairiki.org>
  // You may copy this code freely under the conditions of the GPL.
  //


  // PHP3 does not have assert()
  define('USE_ASSERTS', function_exists('assert'));

  class _DiffOp {
      var $type;
      var $orig;
      var $final;
      

      function norig() {
    return $this->orig ? sizeof($this->orig) : 0;
      }

      function nfinal() {
    return $this->final ? sizeof($this->final) : 0;
      }
  }

  class _DiffOp_Copy extends _DiffOp {
      var $type = 'copy';
      
      function _DiffOp_Copy ($orig, $final = false) {
    if (!is_array($final))
        $final = $orig;
    $this->orig = $orig;
    $this->final = $final;
      }

  }

  class _DiffOp_Delete extends _DiffOp {
      var $type = 'delete';
      
      function _DiffOp_Delete ($lines) {
    $this->orig = $lines;
    $this->final = false;
      }

  }

  class _DiffOp_Add extends _DiffOp {
      var $type = 'add';
      
      function _DiffOp_Add ($lines) {
    $this->final = $lines;
    $this->orig = false;
      }

  }

  class _DiffOp_Change extends _DiffOp {
      var $type = 'change';
      
      function _DiffOp_Change ($orig, $final) {
    $this->orig = $orig;
    $this->final = $final;
      }

  }
    
        
  /**
   * Class used internally by Diff to actually compute the diffs.
   *
   * The algorithm used here is mostly lifted from the perl module
   * Algorithm::Diff (version 1.06) by Ned Konz, which is available at:
   *   http://www.perl.com/CPAN/authors/id/N/NE/NEDKONZ/Algorithm-Diff-1.06.zip
   *
   * More ideas are taken from:
   *   http://www.ics.uci.edu/~eppstein/161/960229.html
   *
   * Some ideas are (and a bit of code) are from from analyze.c, from GNU
   * diffutils-2.7, which can be found at:
   *   ftp://gnudist.gnu.org/pub/gnu/diffutils/diffutils-2.7.tar.gz
   *
   * Finally, some ideas (subdivision by NCHUNKS > 2, and some optimizations)
   * are my own.
   *
   * @author Geoffrey T. Dairiki
   * @access private
   */
  class _DiffEngine
  {
      function diff ($from_lines, $to_lines) {
    $n_from = sizeof($from_lines);
    $n_to = sizeof($to_lines);

    $this->xchanged = $this->ychanged = array();
    $this->xv = $this->yv = array();
    $this->xind = $this->yind = array();
    unset($this->seq);
    unset($this->in_seq);
    unset($this->lcs);
     
    // Skip leading common lines.
    for ($skip = 0; $skip < $n_from && $skip < $n_to; $skip++) {
        if ($from_lines[$skip] != $to_lines[$skip])
      break;
        $this->xchanged[$skip] = $this->ychanged[$skip] = false;
    }
    // Skip trailing common lines.
    $xi = $n_from; $yi = $n_to;
    for ($endskip = 0; --$xi > $skip && --$yi > $skip; $endskip++) {
        if ($from_lines[$xi] != $to_lines[$yi])
      break;
        $this->xchanged[$xi] = $this->ychanged[$yi] = false;
    }
    
    // Ignore lines which do not exist in both files.
    for ($xi = $skip; $xi < $n_from - $endskip; $xi++)
        $xhash[$from_lines[$xi]] = 1;
    for ($yi = $skip; $yi < $n_to - $endskip; $yi++) {
        $line = $to_lines[$yi];
        if ( ($this->ychanged[$yi] = empty($xhash[$line])) )
      continue;
        $yhash[$line] = 1;
        $this->yv[] = $line;
        $this->yind[] = $yi;
    }
    for ($xi = $skip; $xi < $n_from - $endskip; $xi++) {
        $line = $from_lines[$xi];
        if ( ($this->xchanged[$xi] = empty($yhash[$line])) )
      continue;
        $this->xv[] = $line;
        $this->xind[] = $xi;
    }

    // Find the LCS.
    $this->_compareseq(0, sizeof($this->xv), 0, sizeof($this->yv));

    // Merge edits when possible
    $this->_shift_boundaries($from_lines, $this->xchanged, $this->ychanged);
    $this->_shift_boundaries($to_lines, $this->ychanged, $this->xchanged);

    // Compute the edit operations.
    $edits = array();
    $xi = $yi = 0;
    while ($xi < $n_from || $yi < $n_to) {
        USE_ASSERTS && assert($yi < $n_to || $this->xchanged[$xi]);
        USE_ASSERTS && assert($xi < $n_from || $this->ychanged[$yi]);

        // Skip matching "snake".
        $copy = array();
        while ( $xi < $n_from && $yi < $n_to
          && !$this->xchanged[$xi] && !$this->ychanged[$yi]) {
      $copy[] = $from_lines[$xi++];
      ++$yi;
        }
        if ($copy)
      $edits[] = new _DiffOp_Copy($copy);

        // Find deletes & adds.
        $delete = array();
        while ($xi < $n_from && $this->xchanged[$xi])
      $delete[] = $from_lines[$xi++];

        $add = array();
        while ($yi < $n_to && $this->ychanged[$yi])
      $add[] = $to_lines[$yi++];
        
        if ($delete && $add)
      $edits[] = new _DiffOp_Change($delete, $add);
        elseif ($delete)
      $edits[] = new _DiffOp_Delete($delete);
        elseif ($add)
      $edits[] = new _DiffOp_Add($add);
    }
    return $edits;
      }
      

      /* Divide the Largest Common Subsequence (LCS) of the sequences
       * [XOFF, XLIM) and [YOFF, YLIM) into NCHUNKS approximately equally
       * sized segments.
       *
       * Returns (LCS, PTS).  LCS is the length of the LCS. PTS is an
       * array of NCHUNKS+1 (X, Y) indexes giving the diving points between
       * sub sequences.  The first sub-sequence is contained in [X0, X1),
       * [Y0, Y1), the second in [X1, X2), [Y1, Y2) and so on.  Note
       * that (X0, Y0) == (XOFF, YOFF) and
       * (X[NCHUNKS], Y[NCHUNKS]) == (XLIM, YLIM).
       *
       * This function assumes that the first lines of the specified portions
       * of the two files do not match, and likewise that the last lines do not
       * match.  The caller must trim matching lines from the beginning and end
       * of the portions it is going to specify.
       */
      function _diag ($xoff, $xlim, $yoff, $ylim, $nchunks) {
    $flip = false;
    
    if ($xlim - $xoff > $ylim - $yoff) {
        // Things seems faster (I'm not sure I understand why)
        // when the shortest sequence in X.
        $flip = true;
        list ($xoff, $xlim, $yoff, $ylim)
      = array( $yoff, $ylim, $xoff, $xlim);
    }

    if ($flip)
        for ($i = $ylim - 1; $i >= $yoff; $i--)
      $ymatches[$this->xv[$i]][] = $i;
    else
        for ($i = $ylim - 1; $i >= $yoff; $i--)
      $ymatches[$this->yv[$i]][] = $i;

    $this->lcs = 0;
    $this->seq[0]= $yoff - 1;
    $this->in_seq = array();
    $ymids[0] = array();
      
    $numer = $xlim - $xoff + $nchunks - 1;
    $x = $xoff;
    for ($chunk = 0; $chunk < $nchunks; $chunk++) {
        if ($chunk > 0)
      for ($i = 0; $i <= $this->lcs; $i++)
          $ymids[$i][$chunk-1] = $this->seq[$i];

        $x1 = $xoff + (int)(($numer + ($xlim-$xoff)*$chunk) / $nchunks);
        for ( ; $x < $x1; $x++) {
      $line = $flip ? $this->yv[$x] : $this->xv[$x];
      if (empty($ymatches[$line]))
          continue;
      $matches = $ymatches[$line];
      reset($matches);
      while (list ($junk, $y) = each($matches))
          if (empty($this->in_seq[$y])) {
        $k = $this->_lcs_pos($y);
        USE_ASSERTS && assert($k > 0);
        $ymids[$k] = $ymids[$k-1];
        break;
          }
      while (list ($junk, $y) = each($matches)) {
          if ($y > $this->seq[$k-1]) {
        USE_ASSERTS && assert($y < $this->seq[$k]);
        // Optimization: this is a common case:
        //  next match is just replacing previous match.
        $this->in_seq[$this->seq[$k]] = false;
        $this->seq[$k] = $y;
        $this->in_seq[$y] = 1;
          }
          else if (empty($this->in_seq[$y])) {
        $k = $this->_lcs_pos($y);
        USE_ASSERTS && assert($k > 0);
        $ymids[$k] = $ymids[$k-1];
          }
      }
        }
    }

    $seps[] = $flip ? array($yoff, $xoff) : array($xoff, $yoff);
    $ymid = $ymids[$this->lcs];
    for ($n = 0; $n < $nchunks - 1; $n++) {
        $x1 = $xoff + (int)(($numer + ($xlim - $xoff) * $n) / $nchunks);
        $y1 = $ymid[$n] + 1;
        $seps[] = $flip ? array($y1, $x1) : array($x1, $y1);
    }
    $seps[] = $flip ? array($ylim, $xlim) : array($xlim, $ylim);

    return array($this->lcs, $seps);
      }

      function _lcs_pos ($ypos) {
    $end = $this->lcs;
    if ($end == 0 || $ypos > $this->seq[$end]) {
        $this->seq[++$this->lcs] = $ypos;
        $this->in_seq[$ypos] = 1;
        return $this->lcs;
    }

    $beg = 1;
    while ($beg < $end) {
        $mid = (int)(($beg + $end) / 2);
        if ( $ypos > $this->seq[$mid] )
      $beg = $mid + 1;
        else
      $end = $mid;
    }

    USE_ASSERTS && assert($ypos != $this->seq[$end]);

    $this->in_seq[$this->seq[$end]] = false;
    $this->seq[$end] = $ypos;
    $this->in_seq[$ypos] = 1;
    return $end;
      }

      /* Find LCS of two sequences.
       *
       * The results are recorded in the vectors $this->{x,y}changed[], by
       * storing a 1 in the element for each line that is an insertion
       * or deletion (ie. is not in the LCS).
       *
       * The subsequence of file 0 is [XOFF, XLIM) and likewise for file 1.
       *
       * Note that XLIM, YLIM are exclusive bounds.
       * All line numbers are origin-0 and discarded lines are not counted.
       */
      function _compareseq ($xoff, $xlim, $yoff, $ylim) {
    // Slide down the bottom initial diagonal.
    while ($xoff < $xlim && $yoff < $ylim
           && $this->xv[$xoff] == $this->yv[$yoff]) {
        ++$xoff;
        ++$yoff;
    }

    // Slide up the top initial diagonal.
    while ($xlim > $xoff && $ylim > $yoff
           && $this->xv[$xlim - 1] == $this->yv[$ylim - 1]) {
        --$xlim;
        --$ylim;
    }

    if ($xoff == $xlim || $yoff == $ylim)
        $lcs = 0;
    else {
        // This is ad hoc but seems to work well.
        //$nchunks = sqrt(min($xlim - $xoff, $ylim - $yoff) / 2.5);
        //$nchunks = max(2,min(8,(int)$nchunks));
        $nchunks = min(7, $xlim - $xoff, $ylim - $yoff) + 1;
        list ($lcs, $seps)
      = $this->_diag($xoff,$xlim,$yoff, $ylim,$nchunks);
    }

    if ($lcs == 0) {
        // X and Y sequences have no common subsequence:
        // mark all changed.
        while ($yoff < $ylim)
      $this->ychanged[$this->yind[$yoff++]] = 1;
        while ($xoff < $xlim)
      $this->xchanged[$this->xind[$xoff++]] = 1;
    }
    else {
        // Use the partitions to split this problem into subproblems.
        reset($seps);
        $pt1 = $seps[0];
        while ($pt2 = next($seps)) {
      $this->_compareseq ($pt1[0], $pt2[0], $pt1[1], $pt2[1]);
      $pt1 = $pt2;
        }
    }
      }

      /* Adjust inserts/deletes of identical lines to join changes
       * as much as possible.
       *
       * We do something when a run of changed lines include a
       * line at one end and has an excluded, identical line at the other.
       * We are free to choose which identical line is included.
       * `compareseq' usually chooses the one at the beginning,
       * but usually it is cleaner to consider the following identical line
       * to be the "change".
       *
       * This is extracted verbatim from analyze.c (GNU diffutils-2.7).
       */
      function _shift_boundaries ($lines, &$changed, $other_changed) {
    $i = 0;
    $j = 0;

    USE_ASSERTS && assert('sizeof($lines) == sizeof($changed)');
    $len = sizeof($lines);
    $other_len = sizeof($other_changed);

    while (1) {
        /*
         * Scan forwards to find beginning of another run of changes.
         * Also keep track of the corresponding point in the other file.
         *
         * Throughout this code, $i and $j are adjusted together so that
         * the first $i elements of $changed and the first $j elements
         * of $other_changed both contain the same number of zeros
         * (unchanged lines).
         * Furthermore, $j is always kept so that $j == $other_len or
         * $other_changed[$j] == false.
         */
        while ($j < $other_len && $other_changed[$j])
      $j++;
        
        while ($i < $len && ! $changed[$i]) {
      USE_ASSERTS && assert('$j < $other_len && ! $other_changed[$j]');
      $i++; $j++;
      while ($j < $other_len && $other_changed[$j])
          $j++;
        }
        
        if ($i == $len)
      break;

        $start = $i;

        // Find the end of this run of changes.
        while (++$i < $len && $changed[$i])
      continue;

        do {
      /*
       * Record the length of this run of changes, so that
       * we can later determine whether the run has grown.
       */
      $runlength = $i - $start;

      /*
       * Move the changed region back, so long as the
       * previous unchanged line matches the last changed one.
       * This merges with previous changed regions.
       */
      while ($start > 0 && $lines[$start - 1] == $lines[$i - 1]) {
          $changed[--$start] = 1;
          $changed[--$i] = false;
          while ($start > 0 && $changed[$start - 1])
        $start--;
          USE_ASSERTS && assert('$j > 0');
          while ($other_changed[--$j])
        continue;
          USE_ASSERTS && assert('$j >= 0 && !$other_changed[$j]');
      }

      /*
       * Set CORRESPONDING to the end of the changed run, at the last
       * point where it corresponds to a changed run in the other file.
       * CORRESPONDING == LEN means no such point has been found.
       */
      $corresponding = $j < $other_len ? $i : $len;

      /*
       * Move the changed region forward, so long as the
       * first changed line matches the following unchanged one.
       * This merges with following changed regions.
       * Do this second, so that if there are no merges,
       * the changed region is moved forward as far as possible.
       */
      while ($i < $len && $lines[$start] == $lines[$i]) {
          $changed[$start++] = false;
          $changed[$i++] = 1;
          while ($i < $len && $changed[$i])
        $i++;

          USE_ASSERTS && assert('$j < $other_len && ! $other_changed[$j]');
          $j++;
          if ($j < $other_len && $other_changed[$j]) {
        $corresponding = $i;
        while ($j < $other_len && $other_changed[$j])
            $j++;
          }
      }
        } while ($runlength != $i - $start);

        /*
         * If possible, move the fully-merged run of changes
         * back to a corresponding run in the other file.
         */
        while ($corresponding < $i) {
      $changed[--$start] = 1;
      $changed[--$i] = 0;
      USE_ASSERTS && assert('$j > 0');
      while ($other_changed[--$j])
          continue;
      USE_ASSERTS && assert('$j >= 0 && !$other_changed[$j]');
        }
    }
      }
  }

  /**
   * Class representing a 'diff' between two sequences of strings.
   */
  class Diff 
  {
      var $edits;

      /**
       * Constructor.
       * Computes diff between sequences of strings.
       *
       * @param $from_lines array An array of strings.
       *        (Typically these are lines from a file.)
       * @param $to_lines array An array of strings.
       */
      function Diff($from_lines, $to_lines) {
    $eng = new _DiffEngine;
    $this->edits = $eng->diff($from_lines, $to_lines);
      }

  }

        

  /**
   * A class to format Diffs
   *
   * This class formats the diff in classic diff format.
   * It is intended that this class be customized via inheritance,
   * to obtain fancier outputs.
   */
  class DiffFormatter
  {

      /**
       * Format a diff.
       *
       * @param $diff object A Diff object.
       * @return string The formatted output.
       */
      function format($diff) {

    $xi = $yi = 1;
    $block = false;
    $context = array();

    $this->_start_diff();

    foreach ($diff->edits as $edit) {
        if ($edit->type == 'copy') {
      if (is_array($block)) {
          if (sizeof($edit->orig) <= 0) {
        $block[] = $edit;
          }
          else{
        $this->_block($x0, + $xi - $x0,
                $y0, + $yi - $y0,
                $block);
        $block = false;
          }
      }
        }
        else {
      if (! is_array($block)) {
          $x0 = $xi;
          $y0 = $yi;
          $block = array();
      }
      $block[] = $edit;
        }

        if ($edit->orig)
      $xi += sizeof($edit->orig);
        if ($edit->final)
      $yi += sizeof($edit->final);
    }

    if (is_array($block))
        $this->_block($x0, $xi - $x0,
          $y0, $yi - $y0,
          $block);

    return $this->_end_diff();
      }

      function _block($xbeg, $xlen, $ybeg, $ylen, &$edits) {
    $this->_start_block($this->_block_header($xbeg, $xlen, $ybeg, $ylen));
      }

      function _start_diff() {
    ob_start();
      }

      function _end_diff() {
    $val = ob_get_contents();
    ob_end_clean();
    return $val;
      }

      function _block_header($xbeg, $xlen, $ybeg, $ylen) {
    if ($xlen > 1)
        $xbeg .= "," . ($xbeg + $xlen - 1);
    if ($ylen > 1)
        $ybeg .= "," . ($ybeg + $ylen - 1);

    return $xbeg . ($xlen ? ($ylen ? 'c' : 'd') : 'a') . $ybeg;
      }
      
      function _start_block($header) {
    echo $header."\n";
      }

  }

?>